li-etal_2024_james

Structural uncertainty in the sensitivity of urban temperatures to anthropogenic heat flux

Dan Li^1*, Ting Sun², Jiachuan Yang ³, Ning Zhang ⁴, Pouya Vahmani ⁵, and Andrew Jones ⁵

¹ Department of Earth and Environment and Department of Mechanical Engineering, Boston University, Boston, USA ² Department of Risk and Disaster Reduction, University College London, London, UK ³ Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China ⁴ School of Atmospheric Sciences, Nanjing University, Nanjing, China ⁵ Lawrence Berkeley National Laboratory, Berkeley, USA

* corresponding author: [email protected]

Abstract

One key source of uncertainty for weather and climate models is structural uncertainty arising from the fact that these models must simplify or approximate complex physical, chemical, and biological processes that occur in the real world. However, it is rarely examined in the context of simulated effects of anthropogenic heat flux in cities. Using the Weather Research and Forecasting (WRF) model coupled with a single-layer urban canopy model (SLUCM), it is found that the sensitivity of urban canopy air temperature to anthropogenic heat flux can differ by an order of magnitude depending on how anthropogenic heat flux is released to the urban environment. Moreover, varying model structures through changing the treatment of roof-air interaction and the parameterization of convective heat transfer between the canopy air and the atmosphere can affect the sensitivity of urban canopy air temperature by a factor of 4. Urban surface temperature and 2-m air temperature are less sensitive to the methods of anthropogenic heat flux release and the examined model structural variants than urban canopy air temperature, but their sensitivities to anthropogenic heat flux can still vary by as much as a factor of 4 for surface temperature and 2 for 2-m air temperature. Our study recommends using temperature sensitivity instead of temperature response to understand how various physical processes (and their representations in numerical models) modulate the simulated effects of anthropogenic heat flux.

Journal reference

Li et al. (in submission). Structural uncertainty in the sensitivity of urban temperatures to anthropogenic heat flux

Code reference

https://github.com/DanLi-BU/WRF/releases/tag/AH_final

Data reference

Input data

wrfinputs_bdy

Output data

Contributing modeling software

Model	Version	Zenodo
WRF	4.2.2

Reproduce my experiment

1. Install the software components required to conduct the experiement from Contributing modeling software
2. Download and install the supporting input data required to conduct the experiement from Input data
3. Run the following scripts in the WRFscripts directory to re-create this experiment:

Script Name	Description	How to Run
namelist.input	namelist to run the WRF part of my experiment
URBPARM.TBL	an example of URBPARM.TBL where the 3 key entires to change are AHOPTION, ROOF_TO_CANOPY_AIR_OPTION, and CH_SCHEME

4. AHOPTION = 4 in URBPARM.TBL corresponds to method 1 in the manuscript, AHOPTION = 3 corresponds to method 2, AHOPTION = 2 corresponds to method 3, AHOPTION = 5 corresponds to revised method 1
5. ROOF_TO_CANOPY_AIR_OPTION = 0 in URBPARM.TBL corresponds to SVs 1 and 3 in the manuscript, ROOF_TO_CANOPY_AIR_OPTION = 1 corresponds to SVs 2 and 4
6. CH_SCHEME = 100 in URBPARM.TBL corresponds to SVs 3 and 4 in the manuscript, CH_SCHEME = 2 corresponds to SVs 1 and 2

Reproduce my figures

Use the scripts found in the figures directory to reproduce the figures used in this publication. See details in the readme.docx document in the figures directory.